Such an ingestible capsule is known from the international patent application WO 2008/062335, wherein a first part comprising a drug reservoir is secured to a second part comprising a driving mechanism. The drug reservoir has a flexible wall and the driving mechanism has a piston. The driving mechanism is controlled electronically. When the piston is driven into the flexible wall, the pressure inside the reservoir increases and the drug is pushed out of a small opening in the drug reservoir. This displacement controlled pressure based drug delivery device works best with drugs in a more or less liquid form, such as a solution, suspension, emulsion, gel or pasta.
However, for the treatment of many diseases, it would be of great value to have the drug available in powder form. In powder form, the drug has a longer shelf life and is much less prone to degradation. In powder form it often has the highest content of active material per unit volume. The drug delivery device of WO 2008/062335 is not very suitable for delivering the drug in powder form, because a powder is not easily pushed through a small hole.